Pneumatic tires are commonly used on a variety of vehicles, such as passenger automobiles, aircraft, and industrial machinery. It is well known that even a small amount of imbalance in a pneumatic tire mounted to a vehicle can cause undesirable vibration and noise when the tire is rotating at the operating speeds of the vehicle. This imbalance may be attributed to non-uniformities or imperfections in the tire wheel rim, or to imperfections or non-uniformities in the molded tire itself. Such imbalance is particularly noticeable on tires used on aircraft nose landing gear, due to the high wheel speeds, or high revolutions per minute, attained during take-off of the aircraft.
One approach to eliminating or reducing the effects of imbalance in formed tires has been to secure discrete patches of rubber material to the tire innerliner, after the tire has been cured, in an effort to offset any imbalances. Conventional two layered rubber patches or balance pads, which include a thin “adhesive rubber layer” and a thicker “high gravity compound layer”, are commonly used for balancing tires, such as aircraft tires. There also may be one or more other layers placed in-between the two layers to bond them together.
The approach to balancing tires using balance pads requires determining the amount and location of imbalance of the formed tire, typically in a dynamic testing machine. Based upon the results of the imbalance testing, a determination is made as to the location and mass of the patch material needed to counteract the imbalance of the tire. The inner surface of the tire is thereafter cleaned at the appropriate location, typically using an organic solvent, and the patch is adhered at the desired location using one or more solvent-based adhesives, typically rubber-based fast dry cement. Rubber patches commonly used for balancing tires are generally provided in fixed weight increments. One issue of particular importance with tire balancing is obtaining desirable adhesion between balance pads and tire innerliners, particularly with respect to tire innerliners that now utilize dynamically vulcanized alloys.
Dynamically vulcanized alloys (“DVAs”), and in particular DVA films, have been touted as an improved replacement for halobutyl innerliners in tires, at least in part because the films are thinner and lighter than conventional halobutyl innerliners. Yet, in order to have desirable adhesion between conventional balance pads and DVA innerliners, attachment therebetween needs to be addressed. In particular, the DVA is a non-stick material with no inherent tack and includes, in part, an engineering resin, e.g., nylon, as a continuous phase that, unlike conventional halobutyl innerliners, creates a mismatch between the rubber inner rubber layer of conventional balance pads. The end result is that conventional balance pads, which include the rubber based adhesive layers, do not adhere satisfactorily to the DVA innerliner using conventional rubber based fast dry cements.
Accordingly, there is a need in the art for a balance pad for balancing pneumatic tires, which include DVA innerliners, which overcomes the aforementioned drawbacks and disadvantages.